It is known to form a turbine blade with interior compartments, to which relatively cool air from a compressor of an associated gas turbine is fed, and to provide holes in the blade leading edge portion, which holes connect one of those compartments in cooling air flow series with the blade leading edge surface.
It is also known to arrange the holes described hereinbefore in one or more rows, the or each hole being lengthwise of the blade, ie substantially normal to the axis of the associated engine, when the blade is in situ therein, the holes being equally spaced. Further it is known to form the holes so that when the blade is in situ in the engine, the holes axes and engine axis define respective acute angles, such that the air flow through the holes has a directional component radially outwardly of the engine axis.
The known art fails to properly address the cooling needs of cooled turbine blades, having regard to the temperature gradients along their leading edges, and further as a consequence, remove more air than is strictly necessary from the engine system, thus reducing overall engine efficiency.